Control apparatus



Jan. 1, 1946. E, H. LocKwooD CONTROL APPARATUS Filed Sept. ll 1942 2Sheets-Sheet l INVENTOR Evwmx H. L.oc:\f wooo Jan. l, 1946. E. HfLocKwooD CONTROL APPARATUS Filed Sept, 1l

, 1942 2 Sheets-Sheet 2 INVENTOR EDWIN H.Locs wooo ATToRN/W WITNEssEs;

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Patented Jan. 1,1946

ihitii UNITED STATES PATENT OFFiC CGNTROL APPARATUS Edwin H. Lockwood,Manseld, Ohio, assigner to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application september 11,1942. serial No. 457,908

(c1. 21a-2o) 13 Claims.

'I'his invention relates to control apparatus and particularly to animproved time and temperature control device for electric ovens and thelike. and it has for an object to provide an improved device of thecharacter set forth.

Automatic time and temperature controls are well known and generallyvcomprise adjustable thermostatic means for regulating the temperatureof the oven coupled with a clocl: timer. These controls permit theoperator to simultaneously select the baking temperature, the time Iseta dial to indicate the starting time of the cooking operation.

(4) Turn a two-position switch from a position usually identified asmanual to the automatic position, this switch connecting the timer tothe thermostatically-controlled oven circuit.

Upon completion of the baking operation, the operator is required toperform the following operations:

(5)" Return the thermostat knob to its "01f position.

(6) Turn the two-position switch back to its manual setting so that theoven may be used without the timer, if desired.

The above operations have caused trouble because the operators oftenforget to turn the twoposition switch from its manual setting to itsautomatic setting when it is desired to use the timer to control thebaking operation or fail to restore the thermostat knob to its offposition and may neglect to restore the two-position switch to itsmanual setting upon completion of the baking operation. Failure torestore the two position switch to "manual following an automatic bakingoperation leaves the oven heating element circuit open at the timer sothat the oven cannot be used for nonautomatic cooking or baking. It isafeature of the present invention to simplify. the use of electric rangecontrols so that at/the expiration of an automatic baking opera/tion,the oven control is automatically restored to the condition whichpermits manual or nonautornatic control oi' the oven.

It is accordingly o. further object of the present invention to providean improved oven temperam ture regulating and timing system whichautomatically conditions the oven controls for manual operation upon theexpiration oi baking operation employing automatic time and temperaturecontrol.

These and other objects are effected by the invention as will beapparent from the following description and claims taken in connectionwith the accompanying drawings, foi-mins a part ci this application, inwhich:

Fig. i is a perspective view of an electric cook.s ing range in whichthe present invention is iroa corner-ated; I

Fig. 2 is a diagrammatic View of the electric circuits and controlstherefor of the oven heating elements o1' the range shown in Fig. 1, theparte being shown in the position they assume during the Waiting periodof an automatic baking operation;

Fig. 3 is a side elevational view of the temperature-regulating andcircuit-selecting switch unit forming a part of the present invention;

Fig. 4 is a perspective view, looking from below, of a gear employed inthe timer of the present oven control;

Fig. 5 is a perspective view, lookingr from above, of a second gear ofthe timer;

Figs. 6, '7 and 8 are detail views of a portion of the timer mechanismshowing the critical positions of certain parts of the timer.

The electric range l0 illustrated in Fig. 1 may be of conventionalconstruction including surface units I l, the operation of which iscontrolled by knobs l2. The oven. generally indicated I3, is provided.with conventional baking and broiling electric heating elements I4 andI5, respectively. Bakng element I4 preferably takes the form of tworesistors, one located at the bottom of the oven and, the other at thetop and carried by the same support which carries the breil element I5.The heating elements are shown diagrammatically in Fig. 2.

The oven I3 is also provided with a bulb IS of a hydraulic thermostatwhich is connected to a temperature-regulating device, generallyindicated by means of a capillary tube I8. While the invention is shownas employing a hydraulic type of thermostat, it is to be understood thatthe invention is not limited thereto since other Thetemperature-regulating device I1 is of known construction and isenclosed within a housingv which may be mounted conveniently at the rearof the backsplasher, as shown by dotted lines in Fig, 1, with itsadjusting knob I9 accessible at the front. It includes a thermostatwhich is adjusted in a. known manner by means of the knob I9, and whichactuates switch contacts 2| and 22 to control the supply of electricalenergy to the oven heating elements |4 and |5. Manipulation of the knobI 9 also actuates movable contacts 23 and 24 to bring them intoengagement with contacts 25 for connecting the bake elements I4 inseries with contacts EI and 22, or into engagement with contacts 28 toconnect the broil element in series with contacts 2| and 22. The movablecontacts 23 and 24 are also positionable, by means of the knob I9, inthe space between the contacts 25 and 26 so that the elements |4 and Iare open circuited, this position of the movable contacts being the ciposition of' the switch knob I9.

As well understood in the art, when the switch knob i9 is adjusted tomove the contacts 23 and 24 into engagement with contacts 26, that is,the broil setting of the switch knob, the thermostat is simultaneouslyadjusted so that it will not open the contacts 2| and 22 at anytemperature normally encountered when the oven is being used forbroiling.

The switch knob I 3 is movable throughout the major portion. of itsrange, while the contacts 23 and 24 remain in engagement with thecontacts 25. to adiust the thermostat over a wide temperature range. Itis. of course, understood that the thermostat isA calibrated to openthe. contacts 2| and 22 whenever the ovenis at the temperature selectedby the knob I9.

In order to permit the operator or user oi' the range to set the ovencontrols so that a baking operation may be started and completed at alater time. there is providedv a timer, generally indicated 28, which.except as hereinafterlpointed out, may be offconventional construction.This timer comprises the usual clock mechanism and is provided with astart button 29 and a stop buttonl 3|. The start button 29 isv used toset the time at which itis desired to begin a baking operation, whilethev stop button 3| isy used to fix the time at which the bakingoperation is to stop.

Setting of the start button 29 so that a baking operation may be begunat a later time opens a normally closed double-pole switch, generallyindicated 32, this switch being closed at the time selected by the startbutton. By reference to Fig.

2, it will be noted that closing of thev double-pole switch 32 completesa circuit from the supply lines L1 and la, through theclosed switch 32and closed contacts 2,| and 22, closed contacts 23, 24 and 25, tothe-bake elements I4. During the baking period, the circuit is under thecontrol of the thermostat-actuated contacts 2 I and, 22.

Heretofore, it has usually been the practice for the stop mechanism ofthel timer to open the switch 32 at the expiration of the bakingoperation. to thereby deenergize the ovenv heating elements. It has alsobeen necessary for the user to manipulate an auxiliary two-positionswitch or some equivalent device to connect the oven elements and thethermostat switch across the line when the oven was to be used withoutthe auto.- matic timer control. With the present invention, the switch32 remains closed at all times, except during the waiting period fromthe time 'that the timer is set until a baking operation is to begin,and thereby allows the oven to be used solely under the control of thetemperature reglulator or in conjunction with the timer, at wil Toaccomplish this result and to thereby simplify the use of the rangeoven, there is provided a small electric motor 34, here shown as mountedon the housing of the temperature regulator Il, which turns the knob |9back to its "o1 position at the end of a baking period. This motorpreferably includes a speed-reduction unit 35 which drives a slow-speedpinion 36, see Fig. 3. Pinion 36 in turn engages and drives a gear 31connected to the switch shaft 38 by means of a friction clutch 39. Thefriction clutch 39 permits the motor to overrun after the switch knob I9and its shaft 38 have been restored to the off position, without causingany damage to the switch mechanism, and also permits the knob I9 to bemanipulated when the motor is idle.

The shaft 38 carries the knob I9 and is provided with suitable means,such as cams and the like, for manipulating the movable contacts 23 and24 as well as means for adjusting the thermostat.

I The motor 34 is connected to the supply conductor L1 and the neutralconductor N in series with a switch, generally indicated 4|, and is soarranged :that when the switch 4| is closed, the motor, through gears 36and 3l, will turn the switch shaft 38 back to its oii" 'position andthereby shift the movable contacts 23 and 24 to a center positionbetween the contacts 25 and 26 of the oven heating elements. Thus, atthe time the baking operation is to stop; as determined by the settingof the stop button 3|, the timer automatically closes the switch 4| fora brief interval of time, such as vfive minutes. During this time, themotor 34 is energized and it rotates the switch shaft 38vuntil itreaches the oi position. When the switch shaft 38 reaches the oiposition, further movement is prevented by the usual stop, continuedoperation of the motor for the remainder of the interval of time beingpermitted by the clutch 39. An interval of time is chosen which issufticient to assure that the switch is moved all the Way to the offposition regardless of where it may have been set.

At the end of the interval of time, the switch 4| opens to stop'themotor 34 and then it remains open. The automatic cycle is thereuponterminated, leaving the control conditioned for manual operation in theusual manner, that is, the user may, at any time thereafter, obtainheating of the oven by actuating the knob I9 in the usual manner. Sincethe switch 32 is left in closed position, the temperature regulator |`|lis effective when actuated to complete the circuit to one of the heatingelements. Relative movement between the motor 34 and the switch Il uponactuation of the latter is permitted by the clutch 39. Referring to theclock timer 28, it includes suitable mechanism which closes the switch32 at the selected time and leaves it closed until the nexttime-controlled operation. ,Since mechanisms of this character are wellknown, detail description thereof is not necessary.

The clock timer further includes mechanism which operates, whenit isset, to close the switch 4| at the time for which the stop button is setand then does ndt again close the switch 4| l until the nexttime-controlled operation, that is,

asaamo rotatable on the hour shaft. The latter gear 48 is connected toor, in itself, comprises a dial for indicating the stopping time of thebaking operation. Thus, by manipulating the button 3|, gears 46, 41 and48 position the dial to indicate the time at which the baking operationis to stop.

A gear 5|, fixed to the hour shaft 44, engages and drives a gear 52. Thegear 52 as well as the gear 41 is mounted for rotation on a shaft 53suitably supported within the timer housing. The gear 41 is xed againstlongitudinal movement on this shaft while the gear 52 is free to movelongitudinally therealong, as is apparent from a comparison of Figs. 6,7 and 8 which illustrate three critical positions of this gear. Thegears 41 and 52 are normally coupled by means of a pin 54 fixed to thelower gear 52 and receivableV in an opening 55 (see Fig. 4) extendingthrough the gear 41 so that gear 41 is driven by gear 52.

The shaft 53 extends through a channel 56 which is pivoted at 55 to abracket 60 carried by the base 43. This channel carries the gear 52 andis depressible by means of the stop button 3|, against the resistance ofcompression spring 51, to disengage the pin 54 from the opening 55 ingear 41 and thereby unoouple the gears 41 and 52. The free end of thechannel 5B 'is provided with a finger 58, of insulating material, whichextends between and actuates spring arms 59 of the switch 4| as willappear later.

Referring to Fig. 7, the parts are there shown in the position theyassume when the pin 54, carried by the lower gear 52, is disposed withinthe opening 55 of the gear 41. This position of the parts, which may betermed the normal position, represents the condition when the timer isnot being used to control the oven heating elements. When the operatordesires to set the button 3| to condition the control for stopping thebaking operation at s'ome future time, she depresses the button 3| whichcauses the parts to assume the position shown in Fig. 8, where it willbe noted the insulating nger 58 holds the contacts of switch 4| open,and then rotates the knob to set the stop-indicating dial 48. Depressionof the button 3| lowers the pin 54 clear of the opening 55 and thesubsequent rotation of this button rotates the gear 41 so that the topof the pin 54 now rides on the under surface of the gear 41, which nowremains stationary, to maintain the parts in the position shown in Fig.8.

It will be understood that the hour shaft 44 rotates continuously anddrives the gear 52 so that the pin 54 gradually approaches the opening55, the apparatus having been adjusted in the manner described above tobring the pin 54 to the opening 55 at the time set on the dial 48.However, before reaching the opening 55, the pin 54 is biased upwardly,by means of spring 51,

into a shallow recess 6| provided in the underv surface of the gear 41,as shown in Fig. 6. When the pin enters into and rides in this recess,the

switch-actuating nnger is held clear of the contact arms 59 and theswitch 4| is closed.

As'previously pointed out, closing of the switch 4| completes a circuitfor the motor 34 and it restores the adjusting knob I9 and the partsactuated thereby to the off position of the control.

The recess 6l is preferably of such length as to maintain the switch 4|closed for an interval of from five to ten minutes so that by the timethe `pin 54 reaches the opening 55, the motor 34 will have hadsufficient time to restore the control to its oif position. When the pin54 is aligned with the opening 55, the spring 51 forces the pin into theopening, bringing the parts to the position shown in Fig. 7, the motorswitch 4| 'being held open by finger 58.

From the above description, it will be seen that there is provided anautomatic oven control in which the operator need merely'set the knob I9for the desired oven temperature and posi-tion the start and stopbuttons 29 and 3|, respectively, to fix the time at which it is desiredfor the baking operation to begin and the time at which it is desired tohave the baking operation completed. Upon completion of the bakingoperation, no further manipulation of the control is necessary since theknob I9 is automatically restored to its off position and the switch 32remains closed.

While the invention has been shown in but one form, it will be obviousto those vskilled in the art that it is not so limited, but issusceptible of various `changes and modifications without departing fromthe spirit thereof, and it is desired. therefore, that only suchlimitations shall be placed thereupon as are specifically set forth inthe appended claims.

What is claimed is:

1. A control system for electric heating means comprising manuallyadjustable means, thermostatic means, said manually adjustable meansbeing movable to a first position to maintain the heating meanscontinuously deenergized and to at least one other position to provide'energization of the heating means under the control of saidthermostatic means, timer means associated with said thermostatic meansand adjustable to Adelay the energization of said heating means for apreselected period, and adjustable means controlled by said timer meansto automatically restore said manually adjustable means to said firstposition.

2. A control system for electric heating means comprising manuallyadjustable means, said manually adjustable means vbeing movable to afirst position to maintain the heating means continuously deenergizedand to atleast one other position to provide energization of the heatingmeans, timer means associated with said means'and adjustable to delaythe energization-of said heating means for a preselected period, andadjustable means controlled by said timer means to automatically restoresaid manually adjustable means to said first position.

3. A control system for 'electrical heating means comprising a switchmovable to a first position to connect said heating means to a source ofelectrical energy and to a second position to disconnect said heatingmeans from said source of electrical energy, timer means associated withsaid switch and arranged to maintain said heating means deenergized fora preselected period while said switch is in said viirst position andthereafter maintain said heating means energized for a second period,and means controlled by said timer means to move saidswitchto'saidseccnd posi.- tionat the expiration lof said second-period.,

4.a control system for electrical heating means comprising aswitchmovable to a first position to connectl said heating means to a sourceof electrical energy and to a second position to disconnect said heatingmeans from the source of electrical energy, a second switch connected inseries with saidrst-mentioned switch, timer means "arranged to closesaid second switch at a selectable time, and means controlled by ksaidtimer means for moving ysaid first-mentioned ,switch to said secondposition at attimo subse- V,quent to the.V closing of saidsecond-mentioned switch. i 5. A control system` for .electricalA heatingmeans comprising a thermostatically-actuated switch operated in responseto a temperature condition effected by said heating" means, mant ualmeans movable between an "oiT position to at least one active positionfor adjusting said thermostatic means, timer means associated with saidthermostatic means and `arranged to causel energization of said heatingmeans for a pre- .i selected period under the control of said thermoto aposition to maintain the heating means deenergized and to at least oneother position to provide energization of the heating means under thelcontrol of said thermostatic means, and timer means adapted to restoresaid thermostatic means from said other position to the first-mentionedposition atthe expiration of a preselected interval.

7. In a control for a heating'element, a manually-actuated switchmovable to an o position and to a plurality of positions effecting,varying degrees of heating of said heating element, a second switchinseries with said manually-actuated switch, time set means operableascensos tivey tc prevent energization orsaid 'heating ele ment until itis reset, and timing means for mos element, time-controlled means forpreventin;

energization of the heating element, independl ently of the setting ofsaid manually adjuster -means, until a preselected time and thenrendering the `manually adjustable means eifectivl to controlenergization of the heating element and means for terminatingenergization of saic heating element at a preselected later time anc forconditioning the control to energize said heating element upon actuationof said manuallyactuated member.

l1. In a control for controlled apparatus, the combination of a controlmechanism including a manually actuated member movable to a firstposition andto a plurality of operating positions, said controlmechanism operating to effect different conditions of operation of thecontrolled apparatus upon positioning said member in the differentoperating positions, time-controlled means adapted to be set to apreselected rst time and to a preselected second time, means controlledby said time-controlled means and operable upon setting saidtime-controlled means to a pre-selected rst time to interrupt thecontrol of the controlled apparatus by said control mechanism and torestore said control thereto upon the occurrence of said preselectediirst time, and means controlled by the time-controlled means andoperable upon occurrence of the preselected second time to actuate saidmanually-actuated member to said first position.

12. In a control for an electrically-controlled device, the combinationof a control mechanism including switch means controlling a circuitforsaid controlled device and further including a manually-actuated membermovable to an 01T when set to open said second switch until apreselected time and then toclose said switch and to leave it closed,until such means is again set, and time/set means for moving saidmanuallyactuated switch to oi position.

8. In a control for a heating element, the combination ofmanually-actuated switch means movable to` an off position and to aplurality of circuit-closing positions providing varying degrees ofheating', timer mechanism including time setmeans operable when set toopen the circuit until the set timel occurs and then being inoperable toopen the circuit until it is reset and furthe'r including time set meansfor moving said manually-actuated switch..means to the off position atthe set time and being then inoperativeuntil it is again set and the settime occurs, whereby, upon completion of a time-controlled cycle,I saidmanually-actuated switch means be- )comesY operative upon manualactuation.

9. In a control for a heatingr element, the combination ofmanually-actuated switch means movableto anv off position andA to aplurality of circuit-closing positions providing varying degrees ofheating, timing means for preventing energization of said heatingelement, independently of the positionv of said manually-actuatedmember, until Va predetermined or set time, said last-mentioned meansbeing thereafter inoperaposition and to a plurality of operatingpositions, said control mechanism operating said switch means to opensaid circuit upon positioning said member in the 01T Aposition and toeiect difierent conditions of operation of thecontrolled device uponpositioning said member in the diierent operating positions, a'secondswitch connected in said circuit in series with the switch means of saidcontrol mechanism, means for mechanically actuating saidmanually-actuated member to said off position, time-controlled meansadapted to be set to a preselected future on time and operable when soset to cause said'second switch to beopen until the preselected on timeoccurs and thereupon to cause said second switch to close and remaincloseduntil the timecontrolled means is again set to apreselected futureon time, and time-controlled means Idapted to be set to a predeterminedfuture Z5 time and operable to cause said actuating eanstoactuatesaid'member to said oil position when said preselected oiv timeoccurs. l,

13. In a control for electrically-energized apparatus, the combinationof a control mechanism including a manually-actuated member movable toan .off position and to a plurality of operating positions, said controlmechanism serving to prevent energization of `said apparatus when said imember is in the "oil" position and to elect difoperating positions,time-controlled means adapted to be set to a preselected future on" timeand operable when vso set to prevent energization of said apparatusregardless of the position of said member until the Apreselected on timeoccurs and thereupon to restore control of said appara tus to saidcontrol mechanism until said timecontrolled means is again set to an"on" time. and time-controlled means adapted to be set to a preselectedfuture "oif time and operable upon occurrence of said preselected offtime to actuate said manually-actuated member to said off position.

EDWIN H. LOCKWOOD.

